diff --git a/modules/system/classes/PluginManager.php b/modules/system/classes/PluginManager.php
index a6ce922f6..926293ec0 100644
--- a/modules/system/classes/PluginManager.php
+++ b/modules/system/classes/PluginManager.php
@@ -162,6 +162,16 @@ class PluginManager
         $this->registered = true;
     }
 
+    /**
+     * Unregisters all plugins: the negative of registerAll().
+     * @return void
+     */
+    public function unregisterAll()
+    {
+        $this->registered = false;
+        $this->plugins = [];
+    }
+
     /**
      * Registers a single plugin object.
      * @param PluginBase $plugin
diff --git a/tests/unit/system/classes/PluginManagerTest.php b/tests/unit/system/classes/PluginManagerTest.php
index 3a30196cf..b34817c3f 100644
--- a/tests/unit/system/classes/PluginManagerTest.php
+++ b/tests/unit/system/classes/PluginManagerTest.php
@@ -122,7 +122,7 @@ class PluginManagerTest extends TestCase
         $this->assertArrayHasKey('\database\tester', $result);
         $this->assertArrayHasKey('\testvendor\test', $result);
     }
-    
+
     public function testGetVendorAndPluginNames()
     {
         $manager = PluginManager::instance();
@@ -149,4 +149,14 @@ class PluginManagerTest extends TestCase
         $this->assertEquals('Alexey Bobkov, Samuel Georges', $pluginDetails['author']);
     }
 
+    public function testUnregisterall()
+    {
+        $manager = PluginManager::instance();
+        $result = $manager->getPlugins();
+        $this->assertCount(5, $result);
+
+        $manager->unregisterAll();
+        $this->assertEmpty($manager->getPlugins());
+    }
+
 }